[test suite] additional valgrind suppression for pcap-file processing
[test suite] minor test coverage addition for invalid locale setting
[server] call clean_exit() upon check_dir_path() error
[test suite] add GPG_DISABLE_SIG test
[test suite] add invalid gpg sig ID list
[test suite] add invalid sniff interface test
[test suite] extend invalid sniff interface test to include promisc mode